Sex selection is a big thing in evolution. Why does the peacock have a gaudy, useless tail? The only reason we can think of is that drab little peahens like the macho display. The tail says, “look at me! I’m (bird)man enough to survive and thrive while carrying all this useless junk around.” So generation after generation the drab little peahens flock around the guys with the biggest tail and cluck over his eggs, and so generation after generation the little male peachicks are the ones with the genes for the biggest tails. So every generation the pea race gets bigger tails, tempered only by the fact that, you know, a lot of the peacocks sporting big tails probably get eaten.
That’s the theory anyway. It’s the best explanation we can come up with for features that otherwise don’t make sense. (more…)